Added getCellColumnRow function to the Board class

getCellColumnRow is the inverse of getCellIndex. It returns
a 2-element array containing the column and row corresponding
to the given index.
Added Board.getNeighbors function

Board.getNeighbors returns an array containing
up to 4 entries representing the indices of all
the valid (not out of bounds) neighbors
Added a function to find connected components

Board.getConnectedComponents will return an array of
arrays representing the connected components in the
board. Equality is determined with built-in JS equality
operator.